1. Field of the Invention
The present invention relates to an endoscopic system for displaying a color image on a display screen by using data of three primary color images, and particularly to an endoscopic system suitable for observing the state of an object to be photographed which is changing due to a contrast medium.
2. Description of the Prior Art
Usually, to observe a morbid portion such as a portion affected by cancer in an internal organ such as a stomach of a patient by using an endoscopic system, a fluorescent contrast medium is firstly injected into a vein of the patient. After that, a physician observes the cancer portion on a display screen of the endoscopic system to qualitatively inspect with his eyes the amount of blood vessels collecting at the cancer portion.
However, in the prior art endoscopic system, the cancer portion is displayed on the screen as an unclear image thereof because changes in the color of blood vessels after injecting the fluorescent contrast medium into the vein of the patient are so slight to catch. Therefore, it is usually difficult for the physician to correctly diagnose the cancer portion whose color is changing due to the fluorescent contrast medium.
As described in the above, the prior art endoscopic system does not provide on the display a clear image of the cancer portion whose color is changed by the fluorescent contrast medium, and it is difficult with such a prior art endoscopic system to correctly diagnose the degree of progress of the cancer portion.
In addition, the prior art system requires the physician to memorize time when the fluorescent contrast medium has been injected into the vein of the patient, or it requires the physician to actuate a stopwatch simultaneously with the injection. In this way, the physician is forced to do bothersome work with the prior art system.